D-Tagatose is a multi-purpose low-calorie bulk sweetener having non-cariogenic and prebiotic properties. D-Tagatose can be used in food and functional food as well as in pharmaceuticals, cf. U.S. Pat. No. 4,786,722, U.S. Pat. No. 5,356,879 and U.S. Pat. No. 5,447,917.
According to U.S. Pat. No. 5,002,612 and U.S. Pat. No. 5,078,796 D-tagatose has been manufactured by hydrolyzing lactose or a lactose containing material to a mixture of galactose and glucose using a lactase, optionally removing glucose followed by chemical isomerization of galactose to tagatose.
U.S. Pat. No. 6,057,135 describes manufacturing of D-tagatose from cheese whey or milk, which is hydrolyzed to prepare a mixture of galactose and glucose. Glucose is separated from the galactose by fermentation of glucose and subjected to isomerization using L-arabinose isomerase.